Schmincke Aqua Collage Medium

Use Aqua Collage pure or mix it with watercolor on your painting. Then strew or press the elements you're using — for example, textiles, silk paper, pigments, sand — into the wet medium. Aqua Collage is best suited to sticking lightweight collage materials to the support.

It stays water-soluble. However, when mixed with Aqua Fix, it becomes waterproof and can be painted over.